Storage system and a method of operating the storage system

Abstract

A storage system ( 1 ) comprises a plurality of vertical stacks ( 2 ) of storage containers ( 3 ), wherein the stacks ( 2 ) are arranged in a horizontal first direction (X) and a horizontal second direction (Y) which is perpendicular to the first direction (X), a transport unit ( 8 ) for transporting at least one container ( 3 ) to or from a selected stack ( 2 ) in the first and/or second direction (X, Y), and a container handling device ( 9, 10 ) for transferring at least an upper container ( 3 ) from a selected stack ( 2 ) to the transport unit ( 8 ) before the transport unit ( 8 ) including the container ( 3 ) is transported from the selected stack ( 2 ) and for transferring at least a container ( 3 ) from the transport unit ( 8 ) to the top of a selected stack ( 2 ) after the transport unit ( 8 ) including the container ( 3 ) is transported to the selected stack ( 2 ). The transport unit ( 8 ) is movable above the stacks ( 2 ). The container handling device comprises a lifting member ( 9 ) for displacing a selected stack ( 2 ) in vertical direction with respect to adjacent stacks ( 2 ), wherein the lifting member ( 9 ) is movable below the stacks ( 2 ) in a non-lifting condition thereof, and the container handling device comprises an engaging member ( 10 ) that is provided at the transport unit ( 8 ) and suitable for engaging at least an upper container ( 3 ) of a lifted stack so as to retrieve the container or for releasing an engaged container so as to place the container on top of a selected stack.

The invention claimed is: 
     
       1. A storage system comprising:
 a plurality of vertical stacks of storage containers, wherein the stacks are arranged in a horizontal first direction and a horizontal second direction which is perpendicular to the first direction, 
 a transport unit for transporting at least one container to or from a selected stack in the first and/or second horizontal direction, 
 a container handling device for transferring at least an upper container from a selected stack to the transport unit before the transport unit including the container is transported from said selected stack and for transferring at least a container from the transport unit to the top of a selected stack after the transport unit including the container is transported to said selected stack, 
 wherein: 
 the transport unit is movable above the stacks and the transport unit is provided with a first set of wheels at opposite sides of the transport unit for travelling in the first direction and a second set of wheels at opposite sides of the transport unit for travelling in the second direction, wherein at least one of the first and second sets of wheels is liftable with respect to the remainder of the transport unit so as to selectively run either the first set of wheels or the second set of second wheels on top of the stacks or on rails in a grid pattern across the top of the stacks, 
 the container handling device comprises a lifting member for displacing a selected stack in vertical direction with respect to adjacent stacks, 
 the lifting member is movable below the stacks in a non-lifting condition thereof, and 
 the container handling device comprises an engaging member that is provided at the transport unit and suitable for engaging at least an upper container of a lifted stack so as to retrieve said container or for releasing an engaged container so as to place said container on top of a selected stack, and 
 wherein the stacks rest on a support, the lifting member is suitable for displacing a selected stack in vertical direction with respect to the support, and the lifting member is movable below said support in the non-lifting condition thereof. 
 
     
     
       2. The storage system according to  claim 1 , wherein the lifting member comprises a drivable push chain. 
     
     
       3. The storage system according to  claim 2 , wherein the push chain is bendable in two directions which are perpendicular to each other. 
     
     
       4. The storage system according to  claim 3 , wherein the push chain follows a curved path in a horizontally oriented plane when all the stacks rest on the support. 
     
     
       5. The storage system according to  claim 3 , wherein a portion of the push chain follows a helical path, and a vertically oriented portion of the push chain extends within the helical path. 
     
     
       6. The storage system according to  claim 2 , wherein the drivable push chain is mounted on a carriage and rotatable with respect to the carriage about a vertical axis of rotation, and the push chain is guided such that it follows a horizontal and a vertical path during lifting a stack, which vertical path is located at a distance from the axis of rotation. 
     
     
       7. The storage system according to  claim 6 , wherein the carriage is guidable along a guide which is located below the stacks. 
     
     
       8. The storage system according to  claim 6 , wherein the guide is linear. 
     
     
       9. The storage system according to  claim 8 , wherein the transport unit has a container receiving portion including two arms for receiving a container between the arms, and the engaging member comprises at least two holders which are movably mounted to the respective arms and movable towards each other so as to engage a container between the arms. 
     
     
       10. The storage system according to  claim 9 , wherein the holder is part of a slider-crank linkage of which a connecting rod is formed by the holder and of which a slider is mounted to a corresponding arm and movable with respect to the corresponding arm in vertical direction, a first portion of the holder is rotatably mounted to the slider and a second portion of the holder remote from the first portion of the holder is rotatably mounted to a first portion of a crank of the slider-crank linkage, a second portion of the crank remote from its first portion is rotatably mounted to the corresponding arm, and wherein the storage system is provided with an auxiliary transport unit for transporting a plurality of storage containers to or from a selected stack in the first and/or second direction, wherein the auxiliary transport unit is provided with an engaging member for engaging at least an upper container of a lifted stack so as to retrieve said upper container or for releasing an engaged container so as to place said container on top of a selected stack. 
     
     
       11. The storage system according to  claim 10 , wherein the storage system is provided with a storage vehicle for temporarily storing at least a container at a selected stack, which storage vehicle is movable with respect to the stacks in the first and/or second direction and provided with engaging means for engaging at least a container, the storage vehicle is adapted such that when the lifting member lifts the selected stack to a level at which at least two containers project above a top plane in which upper sides of the stacks lie, the engaging means can engage the second container above the top plane, whereby the first container above the top plane is accessible by the transport unit, the transport unit is provided with a first set of wheels at opposite sides of the transport unit for travelling in the first direction and a second set of wheels at opposite sides of the transport unit for travelling in the second direction, wherein at least one of the first and second sets of wheels is liftable with respect to the remainder of the transport unit so as to selectively run either the first set of wheels or the second set of wheels on top of the stacks or on rails in a grid pattern across the top of the stacks, and respective shafts of the wheels of at least one of the first and second sets of wheels are eccentrically and movably mounted to the remainder of the transport unit. 
     
     
       12. The storage system according to  claim 1 , wherein the transport unit has a container receiving portion including two arms for receiving a container between the arms, and the engaging member comprises at least two holders which are movably mounted to the respective arms and movable towards each other so as to engage a container between the arms. 
     
     
       13. The storage system according to  claim 12 , wherein the holder is part of a slider-crank linkage of which a connecting rod is formed by the holder and of which a slider is mounted to a corresponding arm and movable with respect to the corresponding arm in vertical direction, a first portion of the holder is rotatably mounted to the slider and a second portion of the holder remote from the first portion of the holder is rotatably mounted to a first portion of a crank of the slider-crank linkage, and a second portion of the crank remote from its first portion is rotatably mounted to the corresponding arm. 
     
     
       14. The storage system according to  claim 1 , wherein the storage system is provided with an auxiliary transport unit for transporting a plurality of storage containers to or from a selected stack in the first and/or second direction, wherein the auxiliary transport unit is provided with an engaging member for engaging at least an upper container of a lifted stack so as to retrieve said upper container or for releasing an engaged container so as to place said container on top of a selected stack. 
     
     
       15. The storage system according to  claim 1 , wherein the storage system is provided with a storage vehicle for temporarily storing at least a container at a selected stack, which storage vehicle is movable with respect to the stacks in the first and/or second direction and provided with engaging means for engaging at least a container, and the storage vehicle is adapted such that when the lifting member lifts the selected stack to a level at which at least two containers project above a top plane in which upper sides of the stacks lie, the engaging means can engage the second container above the top plane, whereby the first container above the top plane is accessible by the transport unit. 
     
     
       16. A method of operating the storage system of  claim 15 , wherein the location for the first container is clear or made clear by lifting the selected stack through the lifting member until the engaging means of the storage vehicle engages a predetermined container and comprising steps of:
 subsequently lowering the lifting member so as to clear the location between the engaged container and the top plane, and the transport unit puts a replacement container at the clear location, after which the lifting member lifts or lowers the formed stack including the replacement container upon disengaging the engaged container in case of an engaged container until a target container from the stack forms the first container above the top plane so as to enable the transport unit to take away the target container. 
 
     
     
       17. The method according to  claim 16 , wherein the predetermined container is adjacent to the target container. 
     
     
       18. The storage system according to  claim 1 , wherein respective shafts of the wheels of the at least one of the first and second sets of wheels are eccentrically and movably mounted to the remainder of the transport unit. 
     
     
       19. The storage system according to  claim 1 , wherein the storage system is provided with a climbing vehicle which is drivable along a vertical guide at a circumference of the stacks for transporting a container in vertical direction to and from the top of an adjacent stack.